Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby SpaceManMat » Thu Aug 23, 2018 12:43 pm

This seams to be causing some controversy on TRF as well. Also apparently the Go Fast flight altitude was determined by post flight modeling, something I was not aware of. Seems to me we have a growing need to get altitude measurements above 50k. I did see an article about Copenhagen Oribital that they were using unlocked GPS.
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby Viking » Thu Aug 23, 2018 1:28 pm

SpaceManMat wrote:...Seems to me we have a growing need to get altitude measurements above 50k. I did see an article about Copenhagen Oribital that they were using unlocked GPS.

This could still be done with locked GPS.
Using timing GPS modules to synchronize a radio transmitter on board the rocket to receivers on the ground that can then measure the delay (time-of-flight/time-of-arrival) of the radio packets. uBlox claim their timing modules can synchronize "to within 15ns" which works out to a base precision of roughly ~4.5 metres. (the accuracy/granularity of any MCU timer that is measuring the ToF will increase this)
FYI, this is how most lightning trackers work (with the lightning strike being the 'transmitter', three or more receivers to triangulate the position)
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby drew » Thu Aug 23, 2018 4:58 pm

SpaceManMat wrote:This seams to be causing some controversy on TRF as well. Also apparently the Go Fast flight altitude was determined by post flight modeling, something I was not aware of. Seems to me we have a growing need to get altitude measurements above 50k. I did see an article about Copenhagen Oribital that they were using unlocked GPS.


Yea, seems like I stirred up the hornets nest over there... Big thanks to Viking for the uBlox forum find, TBH I should have given you more credit in that post d00d. After rereading it I realised I wasn't exactly clear that you were the one that found it.

And if we're being honest here John Derimig started sniping before I posted about the GPS and lack of lock so I do think he had an axe to grind before I posted.
Andrew Hamilton
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Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby SpaceManMat » Thu Aug 23, 2018 5:02 pm

Viking wrote:
SpaceManMat wrote:...Seems to me we have a growing need to get altitude measurements above 50k. I did see an article about Copenhagen Oribital that they were using unlocked GPS.

This could still be done with locked GPS.
Using timing GPS modules to synchronize a radio transmitter on board the rocket to receivers on the ground that can then measure the delay (time-of-flight/time-of-arrival) of the radio packets. uBlox claim their timing modules can synchronize "to within 15ns" which works out to a base precision of roughly ~4.5 metres. (the accuracy/granularity of any MCU timer that is measuring the ToF will increase this)
FYI, this is how most lightning trackers work (with the lightning strike being the 'transmitter', three or more receivers to triangulate the position)


Probably want to be able to triangulate the transmittion so 3 stations but yes that’s a good method and the accuracy is very acceptable. Easy to verify too by also recording GPS logs when available. The one issues you might get is the clock speed varying due to high Gs.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby SpaceManMat » Thu Aug 23, 2018 5:08 pm

drew wrote:And if we're being honest here John Derimig started sniping before I posted about the GPS and lack of lock so I do think he had an axe to grind before I posted.


Lol - it’s TRF - why pass up the opportunity for a bung fight?
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby drew » Thu Aug 23, 2018 6:19 pm

SpaceManMat wrote:Lol - it’s TRF - why pass up the opportunity for a bung fight?


Strangely I didn't make that post to start a flame war, I was genuinely curious about how CvD came to such an accurate estimation in light of the forum post Viking found. I'm also now quite curious about Derimig's certainty regarding uBlox fixes north of 50k m given Curt's estimate and Greg and Vern's consensus regarding Curt's data and the fact that he had no fix. Greg and Vern aren't fools in this space to put it mildly so it's hard for me to not take them at face value, especially when they have actual data to look at.

TBH though I was more blown away by the fact that Tripoli no longer adheres to certification attempt rules for records. F me, I would NOT want to have to make a judgement call on a cert claim. IMO it's much better to have clearly defined frameworks to apply to these sorts of things.
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Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby SpaceManMat » Thu Aug 23, 2018 7:40 pm

drew wrote:TBH though I was more blown away by the fact that Tripoli no longer adheres to certification attempt rules for records. F me, I would NOT want to have to make a judgement call on a cert claim. IMO it's much better to have clearly defined frameworks to apply to these sorts of things.


Yeah find that really starange. I previously suggested that AMRS should have a seperate records section for flights of interest, I still think this is something that should be considered. Things like the V2 could go in there and attempts like this that are great and inspiring but not offical records. That way we can acknowledge such achievements on their merits without compromising the records process.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby OverTheTop » Thu Aug 23, 2018 8:49 pm

Congrats to CvD for the epic flight. I do find it interesting that with such a flight a GPS capable of working at that altitude was not procured. They are available essentially off the shelf, and with the not insignificant expense of such a large project I would have thought Curt would have gone to the trouble to obtain one for confirmation of altitude.

We can't know what Curt's thoughts were during the project and why this was not on board, so I suppose we just need to congratulate him on the outcome as it stands. Looking forward to seeing your next flight Curt 8) .
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby drew » Fri Aug 24, 2018 9:44 am

OverTheTop wrote:Congrats to CvD for the epic flight. I do find it interesting that with such a flight a GPS capable of working at that altitude was not procured. They are available essentially off the shelf, and with the not insignificant expense of such a large project I would have thought Curt would have gone to the trouble to obtain one for confirmation of altitude.


Could you link to some of those units OTT? I'm nos aware of any GPS chipsets that have this capability documented. And out of curiosity do you know why uBlox stops working above 50km?
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Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby OverTheTop » Fri Aug 24, 2018 1:14 pm

Not sure about uBlox in particular, but probably the COCOM limits it is programmed with I guess.
https://en.wikipedia.org/wiki/Coordinat ... t_Controls

If you Google something like "GPS altitude unlocked" you should be able to find the relevant units to purchase. Price I saw the other day was $250USD.

Other units can be unlocked if you work with the manufacturer and have some degree of trust I think. Not entirely straightforward, but not out of the question either. Should be able to get the altitude unlocked fairly easily if the speed limit is still enabled. People experimenting with high-altitude balloons use this sort of GPS a lot.
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby drew » Fri Aug 24, 2018 2:02 pm

OverTheTop wrote:Not sure about uBlox in particular, but probably the COCOM limits it is programmed with I guess.
https://en.wikipedia.org/wiki/Coordinat ... t_Controls


The Wikipedia COCOM page mentions nothing regarding lock above 50km. It only quotes 18km as a limit which we know isn't the case with uBlox specifically given the diagram Viking shared.

OverTheTop wrote:If you Google something like "GPS altitude unlocked" you should be able to find the relevant units to purchase. Price I saw the other day was $250USD.


Tried that and didn't get any links for purchase of hardware. I did come across the Copenhagen Suborbitals unlocked GPS story from Wired but that is especially light on details.


OverTheTop wrote:Other units can be unlocked if you work with the manufacturer and have some degree of trust I think. Not entirely straightforward, but not out of the question either. Should be able to get the altitude unlocked fairly easily if the speed limit is still enabled. People experimenting with high-altitude balloons use this sort of GPS a lot.


Correct me if I'm wrong but most balloons normally only reach about 120k' in altitude before popping so I'm not entirely sure how helpful the high alt balloon community would be in this specific case.
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Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby OverTheTop » Fri Aug 24, 2018 3:37 pm

Some manufacturers have different interpretations of the COCOM limit, locking out only when both excessive speed and altitude are present. Others seem to have slightly different limits if only one is in excess. Probably depends on how moralistic the manager or programmer are feeling on the day. Seems to be another layer on top of the bureaucracy.

Correct me if I'm wrong but most balloons normally only reach about 120k' in altitude before popping so I'm not entirely sure how helpful the high alt balloon community would be in this specific case.

As for an actual device, here you go: https://www.highaltitudescience.com/col ... t-computer

It looks like some of the cheaper ones will do one or the other (speed/altitude) but the information is scant.

There are some nice SDR solutions if you want to spend a few thousand dollars.

Correct me if I'm wrong but most balloons normally only reach about 120k' in altitude before popping so I'm not entirely sure how helpful the high alt balloon community would be in this specific case.

That's still well above the COCOM regulated 18km level, so the application will be a challenge to some GPS units.
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby Viking » Fri Aug 24, 2018 3:41 pm

From what I've been able to find, COCOM "ceased to function" in 1994 and was superseded by the Wassenaar Arrangement.
GNSS seems to be covered by the 'DUAL-USE LIST - CATEGORY 7 – NAVIGATION AND AVIONICS' however I can't find anything specific.

ITAR apparently had a rule for GNSS :
"· receivers designed for producing navigation results above 60,000 feet altitude and at 1,000 knots velocity or greater"
60,000ft ~= 18km and 1,000kn ~= 515m/s ..... familiar numbers.

Then in 2014 they relaxed the ruling as mentioned here:
http://insidegnss.com/u-s-eases-export- ... receivers/

My guess is that ublox are themselves limiting it to 50km, for reasons unknown.
It would sure be nice if someone from ublox would answer one of the many questions regarding max altitude on their forum.
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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby SpaceManMat » Fri Aug 24, 2018 5:36 pm

Viking wrote:My guess is that ublox are themselves limiting it to 50km, for reasons unknown.
It would sure be nice if someone from ublox would answer one of the many questions regarding max altitude on their forum.


I think the there would be a mine field of historical legislation world wide, why change it if it could potentially limit where you can sell it? Far too much work to figure it all out and extremely little advantage in doing it. So they just make it the way it always worked before.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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Re: Curt von Delius hits 200k' with his Phoenix 4 2 stage stack

Postby drew » Mon Aug 27, 2018 5:28 pm

OverTheTop wrote:As for an actual device, here you go: https://www.highaltitudescience.com/col ... t-computer


Now that's an interesting piece of hardware! Thanks for the share OTT, I'll keep that one in the back of my mind if I ever get to the point where I look to travel north of 50Km.
Andrew Hamilton
AMRS 28 L3
AMRS Records Committee Chairman
Max Alt AGL - 23,908ft - K300 - Balls 22
Max V - 2,488 ft/s, ~Mach 2.2 - M2250 - THUNDA 2015


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